Machine for assembling spark plug electrodes



Aug. 30, 1955 R. K. CHRISTIE ETAL 2,716,267

MACHINE FOR ASSEMBLING SPARK PLUG ELECTRODES Filed June 1, 1951 5Sheets-Sheet l TIE-1' /0 {56 i 7 16 3115 if jg 15 TIE-Z- Bnventors:P0521: T K. CHRIS TIE,

CARL J .FATUN..

(Ittomegs Aug. 30, 1955 R. K. CHRISTIE ETAL MACHINE FOR ASSEMBLING SPARKPLUG ELECTRODES 3 Sheets-Sheet 2 Filed June 1, 1951 Snnentors: QUE/EFTK. CHHIS' TIE EARL JEATUA". @J-u. Q @114 (Zttomeg:

30, 1955 R. K. CHRISTIE HAL 2,716,267

MACHINE FOR ASSEMBLING SPARK PLUG ELECTRODES Filed June 1, 1951 5Sheets-Sheet 3 Z'nwentors EUBBET K. EHHJE TIE,

EARL JEATJN.

QMQW

(Ittornegs United States Patent MACHINE FOR ASSEMBLENG SPARK PLUGELECTRODES Robert K. Christie and Carl 3. Eaton, Toledo, Ohio, as-

signors to Champion Spark Plug Company, Toledo, Ohio, a corporation ofDelaware Application June 1, 1951, Serial No. 229,476

Claims. (Cl. 29-25.19)

This invention relates to the assembly of spark plugs for internalcombustion engines and more particularly to a machine for the automaticcontinuous performance of a sealing material emplacing and tampingoperation in the assembly of spark plug components.

A spark plug basically consists in a pair of electrodes which terminatein spaced electrode points and which are held in position and insulatedfrom each other by an insulator that also forms the main body of theplug. One of the electrodes usually is centrally located and the otherusually is mounted on a shell which is located exteriorly of the bodyand by which the plug is mounted in the engine. The insulator usually isfabricated from a highly specialized ceramic material having thenecessary physical properties and the electrodes and their connectingelements are assembled relative to each other by being rigidlypositioned relative to the ceramic body.

The central electrode of a spark plug may extend nearly to the top ofthe ceramic insulator body and is electrically connected to an upperterminal stud which, in turn, makes an electrical connection with theignition distributing system. The electrode is emplaced in the insulatorafter the insulator has been fabricated and is held in place, in thebest practice, by a sealing and insulating material which fills thespaces between the electrode and the body, serving to securely hold theelectrode in place, to form a gas tight seal between the insulator bodyand the electrode and to insulate the electrode.

Some electrodes extend substantially through the insulator body, formingan annular space with the body. The sealing material fills such space.Other electrodes merely extend downwardly out of the body and, in thiscase, the sealing material may be compacted on top of the electrode witha conductor leading through the material, or the material itself may beelectro-conducting or include electro-conducting substances. In almostall spark plugs, however, certain elements are present in substantiallythe same relationship. The plug has an elongated body and a centralelectrode projecting therefrom and some form of sealing material, forexamples, powders, fibers, combinations of the two, etc., is compactedto hold the two in their proper relationship and stop gas leaks.

Similarly, the insulator body must be mounted in the surrounding shellto properly position these two parts relative to each other and to thecentral electrode and to prevent gas leaks around the insulator.

It is, therefore, the principal object of this invention to provide amachine for automatically charging sealing material in position to holdelectrodes and spark plug insulator bodies in place relative to eachother and for compacting such material at a selected pressure to insureboth that a correct amount of material is used and that the material iscorrectly compacted.

More specifically, it is another object of this invention to provide amachine for automatically placing and compacting sealing material in theinterior of an insulator body for holding and sealing the centralelectrode in place, which machine is provided with means for varying theamount of powder, the tamping pressure, and other considerations inaccordance with the design and style of the spark plugs being assembledand in which the operations take place in a smooth continuous seriesrather than in intermittent step-by-step progression.

These and more specific objects and advantages will be apparent from thespecification and drawings, in which:

Fig. 1 is a vertical sectional view of a machine embodying theinvention, certain parts thereof being shown diagrammatically andcertain parts being broken away.

Fig. 2 is a fragmentary, horizontal, sectional view taken substantiallyon the line 22 of Fig. 1.

Fig. 3 is a horizontal, sectional view taken substantially on the line33 of Fig. 1.

Fig. 4 is a fragmentary, vertical view, partly in elevation and partlyin section and on an enlarged scale, taken on the line 44 of Fig. 1.

Fig. 5 is a fragmentary, greatly enlarged vertical sectional viewillustrating a spark plug body in position to receive and have tamped inplace the central electrode holding and sealing powder.

Fig. 6 is a fragmentary, horizontal, sectional view taken substantiallyon the line 6-6 of Fig. 5.

Fig. 7 is a fragmentary, vertical, sectional view taken on the line 77of Fig. 6.

The embodiment of the invention to be described is designed for thecontinuous automatic assembly of central electrodes and insulator bodiesin which the electrode extends substantially through the body, leavingan annular space into which a powdery sealing material is charged andcompacted. Similar mechanism, embodying many of the features may also beprovided for assembling insulator bodies and outer shells and forcharging and compacting similar material therebetween for sealing thetwo to hold them in position and prevent gas leaks.

A machine embodying the invention may comprise, among other parts, ageneral frame 10 by which the machine is supported on a floor or table.The frame 10 mounts a pair of brackets 11 on which is located a drivingmotor 12. The motor 12, through the medium of a chain 13, drives asprocket 14 which is keyed or otherwise secured on one end of ahorizontally extending worm shaft 15 that is journalled in a pair ofcoaxial bosses 16 formed in the main frame 10. A worm 17 is keyed on theshaft 15 and is engaged with a worm gear 18 keyed or locked on the lowerend of a vertically extending tubular shaft 19 which is journalled byspaced bearings 20 in a cylindrical section 21 of the frame it).

A drum shaped body 22 having a generally cylindrical side wall 23 and agenerally horizontally extending bottom 24 is disposed near the upperend of the tubular shaft 19. The body 22 has a hub 25 which is bolted toa flange 26 on the shaft 19 and which rests on the center race of theupper bearing 20. The body 22 thus rotates with the tubular shaft 19 andmounts a plurality of filling and tamping stations 27 (a completestation being illustrated in cross section in Fig. 4).

Before proceeding further with a description of the machine embodyingthe invention and, in particular, with a description of the uppersection of a spark plug filling and tamping station 27, it is believed adescription of a spark plug body 40 and its center electrode 69 (seeFig. 5) is required. In general, regardless of the particular style orsize of a spark plug, it comprises the sintered ceramic body 40 whichhas a vertically extending center bore 6i, an outer shoulder 62, aconical lower nose portion 63 and an upper shaped portion 64. The bore61 extends entirely through the body 46 and is preferably steppedintermediate its ends to form an internal shoulder 66.

The center electrode 60 is generally rod shaped and is provided with adisc-like flange 67 which rests on the shoulder 66. The lower portion ofthe electrode 68 protrudes through the lower end of the narrow portion65 of the bore'61 and the upper end of the electrode 68 extends almostto the upper end of the portion 64 of the ceramic sintered body 40 whereit receives a stud connection for the ignition system.

Each of the tamping stations 27 has an upper and lower cooperatingsection. The lower section of each of the tamping stations 27 consistsin a hollow cylinder 28 (see also Fig. 4) which is mounted by a sleevebearing 29 for vertical reciprocation in a bracket 3-9 supported in avertical way 31 on the exterior of the cylindrical wall 23 of the drumshaped body 22. Bolts 32 are provided to lock the bracket 30 in place.Each of the hollow cylinders 28 contains a piston 33 which is verticallysiidable within the cylinder 28 and has a washer 34 at its lower end toprovide a fluid tight seal with the cylinder wall 28. A neck 35 of thepiston 33 extends through a central opening in a cylinder cap 36 and awasher 37 provides a fluid seal around the neck 35. At the uppermost endof the neck 35 there is located a removable cap or holding fixture 38having a generally cone-shaped vertical socket 39 (see also Fig. for thereception of a spark plug insulator 4d. The cap 38 is retained in placeon the upper end of the neck by a set screw 41 and can easily be removedfor the substitution of a different sized cap 38 which fits a differenttype or style of spark plug body.

At the lowermost end of the cylinder 28 a horizontally extending openslot 42 is provided for the reception of a rounded end 43 on a generallyhorizontally extending arm of one of a plurality of corresponding bellcrank levers 44, each of which is pivotally mounted by an car 45 securedon the underside of the bottom 24 of the drum shaped body 22. The otherarm of the bell crank lever 44 extends downwardly carrying on its lowerend a roller 46 which rides on the edge of a horizontally extendingprofile cam 47 (see also Fig. 3) which is bolted to the exterior of thecylindrical section 21 of the frame and thus remains stationary whilethe bell crank levers rotate with the body 22.

The lower end of the cylinder 28 is provided with a bore 48 (see Fig. 4)which leads into its interior beneath the piston 33 and is connected bya flexible tube 49 to a fluid manifold 58 secured on the under side ofthe bottom 24 of the drum shaped body 22. The fluid manifold 50 isconnected by piping 51 to a fluid pressure accumulator chamber 52 thatis supported on the upper end of the vertically extending hollow shaft19. The fluid pressure accumulator chamber 52 has a vertical bore 53into which there extends a plunger 54, the upper end of which isprovided with a center post 55 and collar 56 for the reception of aselected number of disc weights 57 A fluid pressure gauge 58 isconnected to a portion of the pipe 51 that extends upwardly through adrum cover 59 and is in communication with the fluid pressure chamber 52and through the piping 51, manifold 50 and tubing 49 with the interiorof each of the vertically movable cylinders 28.

Irrespective, therefore, of the vertical movement of any of thecylinders 28 or the rotation of the drum shaped body 22, a controlledfluid pressure exists within the closed fluid pressure system delineatedby the interior of the conduit and chambers just described and,depending upon the number of weights 57 placed on the collar 56 andacting through the plunger 54, a constant pressure is exerted resistingthe downward movement of each and all of the pistons 33 in theirrespective cylinders 28.

As the drum shaped body 22 rotates the rollers 46 on the lower ends ofthe bell crank levers 44 ride on the periphery of the stationary cam 47and are rocked about their pivots in the ears 45. This raises and lowersthe cylinders 28 in their brackets 30 between the two extreme positionsshown in Fig. l in which the leftside illustrates the lowermost positionof the cylinder 28 corresponding to the lower surfaces of the cam 47 andthe right side of the drawing illustrates the uppermost position of oneof the cylinders 28 which occurs when its corresponding bell crank 44 isswung in a maximum direction counterclockwise by its roller 46 strikingan upper portion of the cam 47.

It is to be understood that the number of spark plug impacting stations27 which are mounted on the exterior of the drum 22 and their associatebell crank levers 44 and flexible tubings 49 is limited solely byphysical con-' siderations, i. e., the number of such stations which canbe mounted upon a drum of a size appropriate for the space in which itis to be housed and the desired number of spark plug parts to beassembled during each period of operation.

As can be seen in Fig. 3 the cam 47 has an elongated dwell surface 68 atone side and this locates the operators station. This elongated dwell 68results in the cylinders 28 remaining at the lower limit of theirmovement while each of them passes this portion of the machine and thisdwell permits an operator to remove a tamped plug and to place a body 40containing a center electrode 60 in each of the holders 38 as it passeshim. As the drum 22 rotates farther in a clockwise direction (Fig. 3)each of the rollers 46 rides up a rise on the cam.

around the center electrode 60 is mounted by means of a.

bracket 71 on each of the ways 31 above each of the reciprocablecylinders 28 and in line therewith and constitutes the upper section ofa tamping station 27. This mechanism consists in parts for dumping ameasured charge of powder, feeding the charge around the centerelectrode 60, tamping the charge in place, clearing the powder feedingneedle and restoring the mechanism for a subsequent charge and temp. Themechanism includes a pair of vertically extending parallel slide rods 72and 73 which are fixedly positioned in a web 74 of the bracket 71 beingsecured thereto by lock nuts 75. A vertically reciprocable slide 76 ismounted to slide up and down on the two slide rods 72 and 73 being urgeddownwardly V thereon by a pair of coiled springs 77 which surround theslide rods 72 and 73 and act between lower faces of the web 74 and apair of washers 78 resting on the upper surface of the slide 76. Theslide 76 consists in a lower plate 79 (see also Fig. 7) which is screwedto a slide block 80. The plate 79 is provided with a generally centrallylocated coned aperture 81 for the reception of the upper. end of thespark plug body 40 (as shown in Fig. 5) to maintain the body coaxialwith the aperture 81. Downward movement of the slide 76 is limited by apair of washers 82 secured by nuts 83 threaded on the lower ends ofslide rods 72 and 73 and limits the travel of the slide as illustratedin Fig. 4.

An oscillating feeder plate 84 is mounted to oscillate on the slide rod72 in a bore 85 in the slide block 80. The feeder plate 84 has agenerally tubular shaped section surrounding the slide rod 72 and a flatextension 86 which has a vertical hole 87 near its end. A pin 88 extendsthrough the cylindrical portion of the plate 84 and is engaged in avertical cam slot 89 milled in the slide rod 72. As the slide 76 movesvertically from the In the position illustrated in solid lines in Fig.6, the 7 hole 87 in the extension 86 of the feeder plate 84 isinvertical alignment with the lower end of a feeder tube 90 (see Figs. 1and 7) which extends through the bracket 71 and is threaded into theslide block 80. A receptacle 91 is located on the upper end of the tube96 and contains a supply of the pulverulent material to be tamped aroundthe center electrode 60.

Thus with each vertical reciprocation of the slide 76, the feeder plate86 is rotated between its two positions, first being rotated in aclockwise direction (Fig. 6) to move a charge of powder contained in thehole 87 over to and above the cone shaped aperture 81 in the plate 79and in line with the open upper end of the bore o1 in the spark plugbody 49. This position of the mechanism with the feeder plate extension86 in the plug charging position is illustrated in Fig. 7 where a plugbody 41) is shown just after having been moved upwardly against theslide plate 79 and the charge of powder 71) is shown as loosely lying inthe annular space surrounding the center electrode 69 in the bore 61.When the tamping has been completed the corresponding cylinder 23 islowered, lowering the spark plug body 49 and allowing the spring toreturn the slide 76 to its lowermost position. During this movement thepin 88 in the cam slot 89 returns the feeder plate extension 86 to theposition shown in the dotted lines in Fig. 6 to receive another chargeof powder in its feeding hole 87.

The means for tamping a charge of powder in place around the centerelectrode consists in a hollow removable tamping tool 92 (see Figs. 4, 5and 7) which is rigidly mounted in the lower end of a tube 93 that is,in turn, adjustably secured in a vertical bore 94 extending through theweb 74 of the bracket 71 between and parallel to the two slide rods 72and 73. The tool 92 to be employed in tamping and sealing and holdingpowders in a selected spark plug body 40 is of such size as to enter andsubstantially fill the annular space surrounding its central electrode6G in its bore 61 and thus for each size and style of spark plug body 40a difierent tamping tool must be employed. Simple demounting meansconsisting in a corresponding cone shaped socket and shoulder 94 on thetool and in the lower end of the tube 93 are provided for seating thetool therein and a transversely extending hole 95 is provided forreceiving a knock out tool 96 (shown in broken lines in Fig. 5). Thetube 93 can be vertically adjusted relative to the tube 74 and thus theposition of the lower end of the tool 92 adjusted relative to theposition of the particular spark plug body being operated on by means ofa pair of lock nuts 97 which are engaged with the exterior of the tube93 and locked above and below the web 74.

The tube 93 is hollow and contains a vertically reciprocable plunger 98at the lower end of which there is fixed a cleaning tool in the form ofa drill 99 which extends downwardly through the center of the tampingtool 92. A spring 100 surrounds an upper smaller diameter portion 101 ofthe plunger 98 and acts between the plunger 98 and a cap 102 closing theupper ends of the tube 93. The portion 101 extends through the cap 162and has a knurled knob 103 aflixed thereto. As the spark plug body ismoved upwardly approaching the position shown in Fig. 5, the lower endof the drill 99 engages with the upper end of the center electrode 6:)and the plunger 98 moves upwardly against its spring 100. This removesthe cleaning drill 99 from the center bore of the tool 92 as the centerelectrode 60 replaces it therein during the time that tamping tool 92 iscompacting the charge of powder around central electrode 69. At thecompletion of the tamping operation the station rotates and as thecylinder 28 is lowered lowering the spark plug body 40, the spring 100correspondingly expands and the cleaning drill 99 follows the centerelectrode down within the bore of the tool 92. Thus the drill 99 ejectsfrom the tool 92 any small amount of powder 70 which may have adheredthereto.

If desired, the cleaning action may be augmented by rotating the cleanintool, and for this purpose a bracket 104 (Figs. 1 and 3) which has afriction surface 105 is mounted to engage each of the knurled knobs 103on the uppermost ends of the plunger 98 at a selected position ofmovement of the machine. This engagement rotates knob 103 and theengaged plunger 98, turning the drill 99 and insuring that the interiorof the corresponding tool 92 remains free of powder.

The tamping of each successive charge of powdered material at theselected tamping pressure is provided for by the fluid pressuremaintained in the closed fluid system earlier described. The weights 57are so selected as to provide the desired fluid pressure beneath each ofthe spark plug body carrying pistons 33 in their corresponding cylinders28. Therefore, as each of the cylinders 28 is moved upwardly, causingthe deposit of a powder charge into the annular space surrounding itscentral electrode 6t), insertion of the tamping tool 92 therein, andfinally the tamping of the charge, the positive upward movement of thecylinder 28 occasioned by the rocking of the bell crank lever 44 thruststhe tamping tool 92 against the loose powder of the last charge made.When the powdered material has been compacted to the desired degree andto compensate for the reduced distance of movement of the tool 92necessary to compact successive charges of powder, the mechanical upwardmovement of the cylinder 28 beyond the distance necessary so to compactthe powder, is compensated for by a downward movement of the piston 33in its cylinder, expelling fluid from the interior of the cylinder 28into the closed fluid system and forcing the weights 57 on their plunger54 upwardly to compensate therefor. Since the weight 57 remains constantduring the entire cycle of operation, the same force is required toraise the weights 57 by transmission of force through the fluid systemand thus each successive charge of powder, although less mechanicalmovement is required to accompany it, is tamped at the selected pressuredetermined by the number of weights 57 acting against the closed fluidsystem. The fluid system is preferably filled with a liquid, althoughgas under pressure may be used.

This upward and downward movement of the plunger 54 and its weights 57may be used to provide for safety switching means to disconnect themotor 12 from its source of power in the event of a jam of one of thetools 92 against a central electrode 60 or plug body which would resultin a compensatory downward movement of the corresponding piston 30 inexcess of that normally to be expected. Conversely, if for some reasonthe tool 92 were to become broken or for other reasons should not pressdownwardly on the powder charge with the desired pressure, insuflicientfluid would be displaced from beneath the corresponding piston 33 andthe plunger 54 and its weights 57 would not be raised but instead woulddrop slightly. Limit switches 106 (see Fig. 1) translate this excessiveor insulficient movement into control for the motor 12.

By positioning the several adjustable means provided in both the upperand lower elements of each tamping station correctly and by theselection of appropriate tools 92 and the correct number of weights 57,a machine embodying the invention can easily and quickly be adjusted totamp the holding and sealing powder around the central electrode of anyone of a large number of varying styles, types and sizes of spark plugs.

The continuous even flowing operation of the machine as contrasted to anintermittent, station-to-station or step-by-step system of operationwhich might be employed, has an advantage in a machine of this typewhere parts are loosely assembled and should be retained in such looselyassembled position until the operations performed on the machine arefinished. For example, if the machine operated intermittently orprogressively from station-to-station, after the spark plug insulatorbody 40 and central electrode were placed in one of the socketsfi9 ylandthe machine then indexed from one station to the next, the abruptstarting or stopping of the I movementquite easily might displace thecomponent parts relative to each other. This undesirable displacement ofparts relative to each other probably would be even more objectionablein a modification of the machine designed for the assembly of insulatorbodies and shells because in most spark plugs the insulator body is manytimes taller than the shell in which it is positioned and thus lessstable when resting loosely therein. However, in the smooth continuousflowing movement around the machine, the component parts of the plugremain properly positioned relative to each other and the continuousrotation of the machine elements allows a very high speed of operationwithout introducing objectionable vibration. The absence of suchvibration resulting from the intermittent starting and stopping of themachine has another advantage in that it eliminates shock loads andserious damage to elements of the machine which would cause highermaintenance costs and reduce the efiective operating time of themachine.

In the modification of the apparatus disclosed, the lower sections ofthe tamping stations 27 have been described as being vertically movableto carry the spark plug bodies upwardly against a stationary tampingtool 92. Under certain conditions as, for example, Where theconstruction of the insulator body and the central electrode or the bodyshell is such that the component parts will not remain in their properrelative positions without being held, or for other reasons, it might bedesirable to move the upper section of the tamping stations downwardlyagainst the plugs. In such a case the lower sections of the tampingstations would remain stationary and the upper sections of the tampingstations would be mounted on vertical reciprocable slides which could bedriven up and down in the same manner as the lower sections areactivated in the mechanism illustrated in the drawings.

In the description of the apparatus constituting the invention, themechanism has been shown as arranged for the charging and compacting ofpowdery sealing material and, for simplicity, the spark plug bodies havebeen shown as extending upward.

Where fibrous sealing material is employed, the charging means may bemodified to control the charges of material and the plug bodies may beheld in a horizontal position to facilitate operations when desired.

If the central electrode does not extend into the core of the insulatorbody, as for example where it is shaped like a plug in the bottom of thebody, the sealing material may be emplaced on top of the electrode .and,in

such cases, the tamping tool 92 would not be a hollow needle but,instead, might be a solid ram,- fitting the interior of the insulatorbody quite closely.

What we claim is:

l. A machine for assembling spark plug bodies and central electrodeshaving elongated upwardly open annular spaces therebetween thatcomprises, in combination, a rotary frame, a plurality of stationsmounted on said frame, each of said stations having a lower sectioncomprising, a vertically reciprocable mount, a support adapted toremovably receive a loosely assembled spark plug body and centralelectrode, said support being vertically movable relative to said mount,and pressure applying means for holding said support in upper positionon said mount and for resisting downward force on said plug and supportwith a selected pressure, mechanism for vertically reciprocating each ofsaid mounts a predetermined distance and a number of reciprocations foreach rotation of said frame, each of said stations also having an uppersection comprising, a bracket, a downwardly directed, hollow tooladapted to enter the annular space between a spark plug body and acentral electrode, said tool being adjustably mounted in said bracket,powder charging meanshaving an actuating element extending below saidtool and engaged by the upper end of a spark plug body for depositing ameasured charge of powder in such annular space prior to the entry ofsaid tool therein, a tool cleaner normally extending downwardly intosaid tool and displaceable upwardly therefrom by said electrode as saidtool enters such annular space, and means for applying a predeterminedpressure to all of said individual station pressure applying meanswhereby each consecutive charge of powder is compacted in each annularspace with the same pressure.

2. In a machine according to claim 1 the improvement in pressureapplying means that consists in a closed fluid system having a cylinderand a pressure piston, means for applying selected weights to saidpiston, an individual closed cylinder in each of said mounts, a supportpiston in each of said individual'cylinders, said support pistonmounting the corresponding one of the spark plug body supports, andmanifolding connecting all of said cylinders in a common system wherebydownward movement of each of said support pistons resulting frompressure of the tamping tool on the powder being compacted is resistedby said. weights acting through said system and when the pressuredetermined thereby is reached no further compaction of the powder takesplace.

3. In a machine according to claim 1, mechanism for verticallyreciprocating the mounts that consists in a stationary cam having aselected number of rises and a longer low section, and a cam followerfor each of said stations linked to the corresponding one of the mountswhereby each mount is raised a predetermined distance, for each rise onsaid cam and remains in lowered position for a section of the rotationof the frame during which an assembled plug body can be removed from thebody support and a plug body and electrode to be assembled can be placedon the body support.

4. In a device according to claim 1, a tool cleaner comprising adrill-like pin extending downwardly into and substantially filling thetool, a shank extending upwardly from said pin, a spring acting to holdsaid pin down and compressed when said pin is moved upwardly, and meansfor rotating said pin periodically when extended entirely into said toolfor removing powder from said tool.

5. A machine for inserting and compacting a measured quantity of sealingpowder ata selected pressure in the elongated annular space between aspark plug body having a shouldered center bore and a central electrodeof smaller diameter that has an annular flange adapted to lie againstthe shoulder in the bore of the spark plug body, said machinecomprising, in combination, a base, a hori zontally rotatable drum-likeframe mounted on said base, means for rotating said frame, a mainhydraulic pressure chamber supported on said frame and having a piston,means for applying a selected pressure to said piston and creating aselected pressure in said chamber, a plurality of spark-plug assemblystations mounted on the outer periphery of said frame, each of saidstations having a lower and upper section, each of said lower sectionscomprising, a vertically slidable mount having a cylindrical hydraulicchamber, a vertically movable piston in said chamber, and a spark plugbody support on said piston, flexible tubing connecting said mainhydraulic pressure chamber to each of said station hydraulic chambers ina common hydraulic system, means for vertically reciproeating each ofsaid mounts a selected number of times during each rotation of saidframe comprising a stationary cam mounted on said base and having aseries of actuating surfaces, a follower for each of said lower sectionsmounted on said frame and engaged with said cam and said section, saidcam having a non-actuating surface corresponding to an operatorsstation, each of said station upper sections comprising a'verticallyadjustable section frame, a downwardly extending hollow tamping toolremovably mounted in said section frame and adapted to enter the annularspace between a spark plug body and a central electrode when a body ismoved upwardly relative thereto, a vertically reciprocable, downwardlyurged 9 slide, engaged by the upper end of a spark plug body prior toentry of said tool into the annular space, and movable upwardlytherewith, means actuated by each upward movement of said slide fordepositing a measured charge of powder in such annular space, arotatable fluted tool cleaning pin extending downwardly into and fillingsaid hollow tool and resilient means urging said pin downwardly, saidpin being displaceable upwardly by entry of References Cited in the fileof this patent UNITED STATES PATENTS Dewar Mar. 2, 1937 Munger et al.July 13, 1948

